Sampada Darling change your H4 to F1 before 4 months of your graduation. You can certainly do that. That makes you pay the Instate tuition and you will also get OPT as soon as you complete. Regarding the work you want to do during your study dont think about that coz you will not earn that much you have gained from Instate Tuition. If you want to work not for money but to improve communication skill try some volunteer work.